This invention is related to the field of organometal catalyst compositions.
The production of polymers is a multi-billion dollar business. This business produces billions of pounds of polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
One of these technologies is called metallocene catalyst technology. Metallocene catalysts have been known since about 1960. However, their low productivity did not allow them to be commercialized. About 1975, it was discovered that contacting one part water with one part trimethylaluminum to form methyl aluminoxane, and then contacting such methyl aluminoxane with a melallocene compound, formed a metallocene catalyst that had greater activity. However, it was soon realized that large amounts of expensive methyl aluminoxane were needed to form an active metallocene catalyst. This has been a significant impediment to the commercialization of metallocene catalysts.
Borate compounds have been used in place of large amounts of methyl aluminoxane. However, this is not satisfactory, since borate compounds are very sensitive to poisons and decomposition, and can also be very expensive.
It should also be noted that having a heterogeneous catalyst is important. This is because heterogeneous catalysts are required for most modem commercial polymerization processes. Furthermore, heterogeneous catalysts can lead to the formation of substantially uniform polymer particles that have a high bulk density. These types of substantially uniformed particles are desirable because they improve the efficiency of polymer production and transportation. Efforts have been made to produce heterogeneous metallocene catalysts; however, these catalysts have not been entirely satisfactory.
Therefore, the inventors provide this invention to help solve these problems.
An object of this invention is to provide a process that produces a catalyst composition that can be used to polymerize at least one monomer to produce a polymer.
Another object of this invention is to provide the catalyst composition.
Another object of this invention is to provide a process comprising contacting at least one monomer and the composition under polymerization conditions to produce the polymer.
Another object of this invention is to provide an article that comprises the polymer produced with the catalyst composition of this invention.
In accordance with one embodiment of this invention, a process to produce a catalyst composition is provided. The process comprises (or optionally, xe2x80x9cconsists essentially ofxe2x80x9d, or xe2x80x9cconsists ofxe2x80x9d) contacting an organometal compound, an organoaluminum compound, and a treated solid oxide compound to produce the catalyst composition,
wherein the organometal compound has the following general formula:
(X1)(X2)(X3)(X4)M1
xe2x80x83wherein
M1 is selected from the group consisting of titanium, zirconium, and hafnium;
wherein (X1) is independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls;
wherein substituents on said substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X1) can be a bridging group which connects (X1) and (X2);
wherein (X3) and (X4) are independently selected from the group consisting of halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein (X2) is selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, substituted fluorenyls, halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein substituents on (X2) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X2) can be a bridging group which connects (X1) and (X2);
wherein the organoaluminum compound has the following general formula:
Al(X5)n(X6)3-n
xe2x80x83wherein
(X5) is a hydrocarbyl having from 1 to about 20 carbon atoms;
wherein (X6) is a halide, hydride, or alkoxide; and
wherein xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive;
wherein the treated solid oxide compound comprises fluorine, chromium, and a solid oxide compound.
In accordance with another embodiment of this invention, a process is provided comprising contacting at least one monomer and the catalyst composition under polymerization condition to produce a polymer.
In accordance with another embodiment of this invention, an article is provided. The article comprises the polymer produced in accordance with this invention.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
Organometal compounds used in this invention have the following general formula:
(X1)(X2)(X3)(X4)M1
In this formula, M1 is selected from the group consisting of titanium, zirconium, and hafnium. Currently, it is most preferred when M1 is zirconium.
In this formula, (X1) is independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-Ixe2x80x9d) cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, such as, for example, tetrahydroindenyls, and substituted fluorenyls, such as, for example, octahydrofluorenyls.
Substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) can be selected independently from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen, as long as these groups do not substantially, and adversely, affect the polymerization activity of the composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Substituted silyl groups include, but are not limited to, alkylsilyl groups where each alkyl group contains from 1 to about 12 carbon atoms, arylsilyl groups, and arylalkylsilyl groups. Suitable alkyl halide groups have alkyl groups with 1 to about 12 carbon atoms. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Suitable examples of such substituents are methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloro, bromo, iodo, trimethylsilyl, and phenyloctylsilyl.
In this formula, (X3) and (X4) are independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-IIxe2x80x9d) halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups, as long as these groups do not substantially, and adversely, affect the polymerization activity of the composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Currently, it is preferred when (X3) and (X4) are selected from the group consisting of halides and hydrocarbyls, where such hydrocarbyls have from 1 to about 10 carbon atoms. However, it is most preferred when (X3) and (X4) are selected from the group consisting of fluoro, chloro, and methyl.
In this formula, (X2) can be selected from either Group OMC-I or Group OMC-II.
At least one substituent on (X1) or (X2) can be a bridging group that connects (X1) and (X2), as long as the bridging group does not substantially, and adversely, affect the activity of the composition. Suitable bridging groups include, but are not limited to, aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, phosphorous groups, nitrogen groups, organometallic groups, silicon, phosphorus, boron, and germanium.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffms, cycloolefins, cycloacetylenes, and arenes. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Various processes are known to make these organometal compounds. See, for example, U.S. Pat. Nos. 4,939,217; 5,210,352; 5,436,305; 5,401,817; 5,631,335, 5,571,880; 5,191,132; 5,480,848; 5,399,636; 5,565,592; 5,347,026; 5,594,078; 5,498,581; 5,496,781; 5,563,284; 5,554,795; 5,420,320; 5,451,649; 5,541,272; 5,705,478; 5,631,203; 5,654,454; 5,705,579; and 5,668,230; the entire disclosures of which are hereby incorporated by reference.
Specific examples of such organometal compounds are as follows:
bis(cyclopentadienyl)hafnium dichloride; 
bis(cyclopentadienyl)zirconium dichloride; 
1,2-ethanediylbis(xcex75-1-indenyl)di-n-butoxyhafnium; 
1,2-ethanediylbis(xcex75-1-indenyl)dimethylzirconium; 
3,3-pentanediylbis(xcex75-4,5,6,7-tetrabydro-1-indenyl)hafnium dichloride; 
methylphenylsilylbis(xcex75-4, 5,6, 7-tetrahydro-1-indenyl)zirconium dichloride; 
xe2x80x9cbis(n-butylcyclopentadienyl)di-t-butylamidohafniumxe2x80x9d
bis(n-butylcyclopentadienyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl)zirconium dichloride; 
xe2x80x9cnonyl(phenyl)silylbis(1-indenyl)hafnium dichloridexe2x80x9d 
dimethylsilylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride; 
dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride; 
1,2-ethanediylbis(9-fluorenyl)zirconium dichloride; 
indenyl diethoxy titanium(IV) chloride; 
(isopropylamidodimethylsilyl)cyclopentadienyltitanium dichloride; 
bis(pentamethylcyclopentadienyl)zirconium dichloride; 
bis(indenyl) zirconium dichloride; 
methyloctylsilyl bis (9-fluorenyl) zirconium dichloride; 
bis-[1-(N,N-diisopropylamino)boratabenzene]hydridozirconium trifluoromethylsulfonate 
Preferably, the organometal compound is selected from the group consisting of
bis(n-butylcyclopentadienyl)zirconium dichloride; 
bis(indenyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl) zirconium dichloride; 
methyloctylsilylbis(9-fluorenyl)zirconium dichloride 
Organoaluminum compounds have the following general formula:
Al(X5)n(X6)3-n
In this formula, (X5) is a hydrocarbyl having from 1 to about 20 carbon atoms. Currently, it is preferred when (X5) is an alkyl having from 1 to about 10 carbon atoms. However, it is most preferred when (X5) is selected from the group consisting of methyl, ethyl, propyl, butyl, and isobutyl.
In this formula, (X6) is a halide, hydride, or alkoxide. Currently, it is preferred when (X6) is independently selected from the group consisting of fluoro and chloro. However, it is most preferred when (X6) is chloro.
In this formula, xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive. However, it is preferred when xe2x80x9cnxe2x80x9d is 3.
Examples of such compounds are as follows:
trimethylaluminum;
triethylaluminum (TEA);
tripropylaluminum;
diethylaluminum ethoxide;
tributylaluminum;
diisobutylaluminum hydride;
triisobutylaluminum hydride;
triisobutylaluminum; and
diethylaluminum chloride.
Currently, TEA is preferred.
The treated solid oxide compound comprises fluorine, chromium, and a solid oxide compound. The solid oxide compound can be any oxide compound known in the art capable of being impregnated with chromium and fluorine. Exemplary solid oxide compounds, include, but are not limited to, inorganic oxides, either alone or in combination, phosphated inorganic oxides, and mixtures thereof Preferably, the solid oxide compound is selected from the group consisting of alumina, silica-titania, aluminophosphate, silica-alumina, and mixtures thereof.
When a silica-titania is used, the content of titania can be about 1 to about 15% by weight titanium based on the total weight of the silica-titania, preferably, about 2.5 to about 12% by weight, and most preferably, 4 to 10% by weight, with the remainder being primarily silica. The silica-titania can be produced by any method known in the art. Such processes are disclosed in U.S. Pat. Nos. 3,887,494; 3,119,569; 4,405,501; 4,436,882; 4,436,883; 4,392,990; 4,081,407; 4,152,503; 4,981,831; 2,825,721; 3,225,023; 3,226,205; 3,622,521; and 3,625,864; the entire disclosures of which are hereby incorporated by reference. The silica-titania can be made by cogellation of aqueous materials, or by cogellation in an organic or anhydrous solution, or by coating the surface of silica with a layer of titania such as, for example, by reaction of silanol groups with titanium isopropoxide followed by calcining.
Aluminophosphate can be made by any method known in the art, such as, for example, those methods disclosed in U.S. Pat. Nos. 4,364,842, 4,444,965; 4,364,855; 4,504,638; 4,364,854; 4,444,964; 4,444,962; 4,444,966; and 4,397,765; the entire disclosures of which are hereby incorporated by reference.
Silica-alumina can be made by any method known in the art. The amount of alumina in the silica-alumina can range from about 2 to about 50% by weight based on the total weight of the silica-alumina, preferably, from about 5 to about 30% by weight, and most preferably, 8 to 20% by weight. Commercial grade silica-alumina is available as MS 13-110 from W. R. Grace and commercial grade alumina as Ketjen Grade B from Akzo Nobel.
The solid oxide compound should have a pore volume greater than about 0.5 cc/g, preferably greater than about 0.8 cc/g, and most preferably, greater than 1.0 cc/g.
The solid oxide compound should have a surface area in a range of about 100 to about 1000 m2/g, preferably from about 200 to about 800 m2/g, and most preferably, from 250 to 600 m2/g.
To prepare the treated solid oxide compound, the solid oxide compound must be impregnated with a chromium-containing compound to produce a chromium-containing solid oxide compound. The chromium-containing compound can be incorporated during manufacturing of the solid oxide compound, such as, for example, during a gellation or spray drying process. For example, in a first method, chromium can be added to the solid oxide compound by cogellation of aqueous materials, as represented in U.S. Pat. Nos. 3,887,494; 3,119,569; 4,405,501; 4,436,882; 4,436,883; 4,392,990; 4,081,407; 4,981,831; and 4,152,503; the entire disclosures of which were previously incorporated by reference. In a second method, the chromium can be added to the solid oxide compound by cogellation in an organic or anhydrous solution as represented by U.S. Pat. Nos. 4,301,034; 4,547,557; and 4,339,559; the entire disclosures of which are hereby incorporated by reference.
Alternatively, the chromium-containing compound can be applied after the solid oxide compound is produced in a post-impregnation step, in which the chromium-containing compound is dissolved in an aqueous or organic solvent and used to impregnate the solid oxide compound. Exemplary methods of impregnating the solid oxide compound with the chromium-containing compound can be found, but are not limited to, U.S. Pat. Nos. 3,976,632; 4,2248,735; 4,297,460; and 4,397,766; the entire disclosures of which are hereby incorporated by reference.
The chromium-containing compound can be any compound capable of being converted to chromium oxide during calcining. Calcining is discussed subsequently in this disclosure. Examples of chromium-containing compounds include, but are not limited to, chromium trioxide (CrO3), ammonium chromate ((NH4)2CrO4), ammonium dichromate ((NH4)2Cr2O7), chromic acetate (Cr(C2H3O2)3), chromic nitrate, (Cr(NO3)3), chromous chloride (CrCl2), bis-benzene chromium(0) ((C6H6)2Cr), chromocene ((C5H5)2Cr), and mixtures thereof.
The amount of chromium present is in the range of about 0.01 to about 10% by weight, preferably, about 0.5 to about 5% by weight, and most preferably, from 0.8% to 3% by weight, where the weight percents are based on the weight of the chromium-containing solid oxide compound before calcining.
Before, during, or after contacting the solid oxide compound with the chromium-containing compound, the solid oxide compound is contacted with a fluorine-containing compound. The order of contacting the solid oxide compound with the chromium-containing compound and the fluorine-containing compound is not important to the production of the treated solid oxide compound. Any method known in the art for contacting the solid oxide compound with the fluorine-containing compound can be used in this invention. One common method is to impregnate the solid oxide compound with an aqueous solution of a fluoride-containing salt, such as, for example, ammonium fluoride (NH4F), ammonium bifluoride (NH4HF2), hydrofluoric acid (HF), ammonium silicofluoride ((NH4)2SiF6), ammonium fluoroborate (NH4BF4), ammonium fluorophosphate (NH4PF6), fluoroboric acid (HBF4), and mixtures thereof. Alternatively, the fluorine-containing compound can be dissolved into an organic solvent, such as an alcohol, and used to impregnate the solid oxide compound to minimize shrinkage of pores during drying. Drying can be accomplished by any method known in the art such as vacuum drying, spray drying, flash drying, and the like.
The fluorine-containing compound can also be incorporated into a gel by adding it to one of the aqueous materials before gellation. These aqueous materials were disclosed in the first and second methods for preparing the chromium-containing solid oxide compound discussed previously in this disclosure.
The fluorine-containing compound can also be added to a slurry containing a gel before drying. Formation of a gel was disclosed in the first and second methods for preparing the chromium-containing solid oxide compound discussed previously in this disclosure.
The fluorine-containing compound can also be added during calcining. In this technique, the fluorine-containing compound is vaporized into a gas stream used to fluidize the solid oxide compound so that it is fluorided from the gas stream. In addition to some of the fluorine-containing compounds described above, volatile organic fluorides may be used at temperatures above their decomposition points, or at temperatures high enough to cause reaction. For example, perfluorohexane, perfluorobenzene, trifluoroacetic acid, trifluoroacetic anhydride, hexafluoroacetylacetonate, and mixtures thereof can be vaporized and contacted with the solid oxide compound or the chromium-containing solid oxide compound at about 300 to about 600xc2x0 C. in air or nitrogen. Inorganic fluorine containing vapors may also be used, such as, for example, hydrogen fluoride or even elemental fluorine gas.
The solid oxide compound or chromium-containing solid oxide compound can also be calcined at a temperature in a range of about 100 to 900xc2x0 C. before being fluorided.
The amount of fluorine present is about 1 to about 50% by weight fluorine based on the weight of the solid oxide compound before calcining. Preferably, it is about 3 to about 25% by weight, and most preferably, it is 4 to 20% by weight fluorine based on the weight of the solid oxide compound before calcining.
Generally, calcining is conducted for about 1 minute to about 100 hours, preferably for about 1 hour to about 50 hours, and most preferably, from 3 hours to 20 hours. The calcining is conducted at a temperature in a range of about 200 to about 900xc2x0 C., preferably, in a range of about 300 to about 700xc2x0 C., and most preferably, in a range of 350 to 600xc2x0 C. Calcining must be conducted in an oxidizing atmosphere, such as, for example, oxygen or air, where at least a portion of the chromium is converted into a hexavalent state. Optionally, a reducing atmosphere such as, for example, hydrogen or carbon monoxide, can be used during calcining as is known in the art. A final calcining step in carbon monoxide at about 350xc2x0 C. can be used to convert the chromium to a divalent state, which produces a catalyst that can be used to produce hexene during polymerization thus allowing in-silu production of comonomer and thus the production of copolymer from an ethylene feed. This process is described in U.S. Pat. Nos. 4,735,931, 4,820,785, and 4,988,657; the entire disclosures of which are hereby incorporated by reference. The calcining can also be accomplished in a reducing atmosphere at a temperature in the range of about 250 to 700xc2x0 C., preferably from 300 to 500xc2x0 C. followed by calcining in an oxidizing atmosphere, which produces a catalyst that will yield a polymer with an increased melt index. This process is described in U.S. Pat. Nos. 4,151,122; 4,177,162; 4,247,421; 4,248,735; 4,297,460; 4,397,769; and 4,460,756; the entire disclosures of which are hereby incorporated by reference.
The compositions of this invention can be produced by contacting the organometal compound, the treated solid oxide compound, and the organoaluminum compound, together. This contacting can occur in a variety of ways, such as, for example, blending. Furthermore, each of these compounds can be fed into the reactor separately, or various combinations of these compounds can be contacted together before being further contacted in a reactor zone, or all three compounds can be contacted together before being introduced into the reactor zone.
Currently, one method is to first contact the organometal compound and the treated solid oxide compound together, for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 100xc2x0 C., preferably 15xc2x0 C. to 50xc2x0 C., to form a first mixture, and then contact this first mixture with an organoaluminum compound to form the catalyst composition.
Another method is to precontact the organometal compound, the organoaluminum compound, and the treated solid oxide compound before injection into a polymerization reactor for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 20xc2x0 C. to 80xc2x0 C. to produce the catalyst composition.
The weight ratio of the organoaluminum compound to the treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
The weight ratio of the treated solid oxide compound to the organometal compound in the composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. These ratios are based on the amount of the components combined to give the catalyst composition.
After contacting, the catalyst composition comprises a post-contacted organometal compound, a post-contacted organoaluminum compound, and a post-contacted treated solid oxide compound. Preferably, the post-contacted treated solid oxide compound is the majority, by weight, of the composition. Often times, specific components of a catalyst are not known, therefore, for this invention, the catalyst composition is described as comprising post-contacted compounds.
The weight ratio of the post-contacted organoaluminum compound to the post-contacted treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
The weight ratio of the post-contacted treated solid oxide compound to the post-contacted organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1.
The catalyst composition of this invention has an activity greater than a catalyst composition that uses the same organometal compound, and the same organoaluminum compound, but uses silica, fluorided silica, silica-titania, alumina, or silica-alumina, as an activator for the organometal compound as shown in comparative examples 1-3, 5 and 7. The activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of about 50 to about 110xc2x0 C., and an ethylene pressure of about 400 to about 800 psig. When comparing activities, the polymerization runs should occur at the same polymerization conditions. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
However, it is preferred if the activity is greater than about 500 grams of polymer per gram of treated solid oxide compound per hour, more preferably greater than about 1000, and most preferably greater than 2000. This activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of 90xc2x0 C., and an ethylene pressure of 550 psig. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
One of the important aspects of this invention is that no aluminoxane needs to be used in order to form the catalyst composition. Aluminoxane is an expensive compound that greatly increases polymer production costs. This also means that no water is needed to help form such aluminoxanes. This is beneficial because water can sometimes kill a polymerization process. Additionally, it should be noted that no borate compounds need to be used in order to form the catalyst composition. In summary, this means that the catalyst composition, which is heterogenous, and which can be used for polymerizing monomers, can be easily and inexpensively produced because of the substantial absence of any aluminoxane compounds or borate compounds. Additionally, no organochromium compounds or MgCl2 need to be added to form the invention. Although aluminoxane, borate compounds, organochromium compounds, or MgCl2 are not needed in the preferred embodiments, these compounds can be used in other embodiments of this invention.
In another embodiment of this invention, a process comprising contacting at least one monomer and the catalyst composition to produce at least one polymer is provided. The term xe2x80x9cpolymerxe2x80x9d as used in this disclosure includes homopolymers and copolymers. The catalyst composition can be used to polymerize at least one monomer to produce a homopolymer or a copolymer. Usually, homopolymers are comprised of monomer residues, having 2 to about 20 carbon atoms per molecule, preferably 2 to about 10 carbon atoms per molecule. Currently, it is preferred when at least one monomer is selected from the group consisting of ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-I-pentene, 4-methyl-1-pentene, 1-hexene, 3-ethyl-1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and mixtures thereof
When a homopolymer is desired, it is most preferred to polymerize ethylene or propylene. When a copolymer is desired, the copolymer comprises monomer residues and one or more comonomer residues, each having from about 2 to about 20 carbon atoms per molecule. Suitable comonomers include, but are not limited to, aliphatic 1-olefins having from 3 to 20 carbon atoms per molecule, such as, for example, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, and other olefins and conjugated or nonconjugated diolefins such as 1,3-butadiene, isoprene, piperylene, 2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 1,7-hexadiene, and other such diolefins and mixtures thereof. When a copolymer is desired, it is preferred to polymerize ethylene and at least one comonomer selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. The amount of comonomer introduced into a reactor zone to produce a copolymer is generally from about 0.01 to about 10 weight percent comonomer based on the total weight of the monomer and comonomer, preferably, about 0.01 to about 5, and most preferably, 0.1 to 4. Alternatively, an amount sufficient to give the above described concentrations, by weight, in the copolymer produced can be used.
Processes that can polymerize at least one monomer to produce a polymer are known in the art, such as, for example, slurry polymerization, gas phase polymerization, and solution polymerization. It is preferred to perform a slurry polymerization in a loop reaction zone. Suitable diluents used in slurry polymerization are well known in the art and include hydrocarbons which are liquid under reaction conditions. The term xe2x80x9cdiluentxe2x80x9d as used in this disclosure does not necessarily mean an inert material; it is possible that a diluent can contribute to polymerization. Suitable hydrocarbons include, but are not limited to, cyclohexane, isobutane, n-butane, propane, n-pentane, isopentane, neopentane, and n-hexane. Furthermore, it is most preferred to use isobutane as the diluent in a slurry polymerization. Examples of such technology can be found in U.S. Pat. Nos. 4,424,341; 4,501,885; 4,613,484; 4,737,280; and 5,597,892; the entire disclosures of which are hereby incorporated by reference.
The catalyst compositions used in this process produce good quality polymer particles without substantially fouling the reactor. When the catalyst composition is to be used in a loop reactor zone under slurry polymerization conditions, it is preferred when the particle size of the solid oxide compound is in the range of about 10 to about 1000 microns, preferably about 25 to about 500 microns, and most preferably, 50 to 200 microns, for best control during polymerization.
In a more specific embodiment of this invention, a process is provided to produce a catalyst composition, the process comprising (optionally, xe2x80x9cconsisting essentially ofxe2x80x9d, or xe2x80x9cconsisting ofxe2x80x9d):
(1) contacting a solid oxide compound selected from the group consisting of alumina, silica-alumina, and silica-titania with an aqueous solution containing chromic acetate and ammonium bifluoride to produce a fluorided, chromium-containing solid oxide compound having from 0.8% to 3% by weight chromium per gram of fluorided, chromium-containing solid oxide compound before calcining and 4 to 20% by weight fluorine based on the weight of the fluorided, chromium-containing solid oxide compound before calcining;
(2) calcining the fluorided, chromium-containing solid oxide compound at a temperature within a range of 350 to 600xc2x0 C. for 3 to 20 hours to produce a calcined composition;
(3) combining the calcined composition and bis(n-butylcyclopentadienyl) zirconium dichloride at a temperature within the range of 15xc2x0 C. to 50xc2x0 C. to produce a mixture; and
(4) after between 1 minute and 1 hour, combining the mixture and triethylaluminum to produce the catalyst composition.
Hydrogen can be used with this invention in a polymerization process to control polymer molecular weight.
The main feature of this invention is that the treated solid oxide compound is an active catalyst, and it also activates the organometal compound. Thus, the polymer produced can be considered a dual component or bimodal polymer. The treated solid oxide compound provides a high molecular weight component onto an otherwise symmetrical molecular weight distribution of the polymer produced by the organometal compound. This high molecular weight component, or skewed molecular weight distribution, imparts higher melt strength and shear response to the polymer than could be obtained from typical organometal compounds. One special feature of this invention, therefore, is that polydispersities of about 2.5 to about 4.0 and HLMI/MI values from about 25 to about 50 can be produced from organometal compounds that would otherwise give polydispersities of about 2.1 to about 2.5 and HLMI/MI values less than about 20.
After the polymers are produced, they can be formed into various articles, such as, for example, household containers and utensils, film products, drums, fuel tanks, pipes, geomembranes, and liners. Various processes can form these articles. Usually, additives and modifiers are added to the polymer in order to provide desired effects. It is believed that by using the invention described herein, articles can be produced at a lower cost, while maintaining most, if not all, of the unique properties of polymers produced with organometal compounds.